This invention relates to suppressing hydrocarbon and carbon monoxide emissions from internal combustion engines, and, more particularly, to a catalyst and method of preparing the catalyst which oxidizes hydrocarbons (HC) and carbon monoxide (CO) to carbon dioxide and water.
In accordance with the invention platinum and palladium are deposited on different substrates. For example, the substrate may be alumina pellets in the form of spheres, cylinders, or other shapes, and platinum is deposited on one group of substrates and palladium is deposited on another group of substrates. The platinum-containing pellets and the palladium-containing pellets are then mixed, and the mixed pellets are placed in the path of an exhaust stream of an internal combustion engine. If desired, either or both of the platinum and palladium which is deposited on the substrate pellets can be complexed with ammonia.
Specific examples of the invention are set forth below as illustrative.